Reciprocating pump

ABSTRACT

A reciprocating pump comprising a pump casing having a cylinder chamber and a plunger driving chamber, a diaphragm being provided in the plunger driving chamber and defining a space with a partition separating the chambers. A hollow elastic damping body is mounted in the space between the diaphragm and the partition and the hollow body communicates with the ambient atmosphere.

United States Patent H 1 Ito [ 1 RECIPROCATING PUMP [76] Inventor: Kazuichi Ito, 1463-4, lchibu-cho,

lkoma-shi, Nara-ken, Japan [22] Filed: Oct. 31, 1973 [2]] Appl. No.: 411,410

[30] Foreign Application Priority Data June 4, 1973 Japan 48-61833 [52] US. Cl. 417/284; 417/437; 92/85; 92/90; 92/97; 74/182 [51] Int. Cl. F041! 49/00 [58] Field 01 Search 92/85, 90, 91, 92, 96, 92/97; 74/182; 417/284, 437

[56] References Cited UNITED STATES PATENTS Puckett 92/92 11 3,884,597 [451 May 20, 1975 3,118,389 1/1964 Camp 74/182 3,299,828 1/1967 Josephian 74/182 3,415,198 12/1968 Lappo 417/503 Primary ExaminerWi1liam L. Frceh [57] ABSTRACT A reciprocating pump comprising a pump casing having a cylinder chamber and a plunger driving chamber, a diaphragm being provided in the plunger driving chamber and defining a space with a partition separating the chambers. A hollow elastic damping body is mounted in the space between the diaphragm and the partition and the hollow body communicates with the ambient atmosphere.

10 Claims, 1 Drawing Figure lufillll RECIPROCATING PUMP BACKGROUND OF THE INVENTION a. Field of the Invention The present invention relates to a reciprocating pump incorporating a plunger and a diaphragm or bellows.

b. Description of the Prior Art The basic principle of such type of reciprocating pump is explained in the specification of Japanese Pat. application No. 72310/72 filed on July l8, i972 by the same Applicant as in the present Application.

A reciprocating pump in accordance with this principle has the advantages of both the plunger type and the diaphragm type of reciprocating pumps while obviating the disadvantages thereof.

Namely, the above described reciprocating pump incorporating a plunger and a diaphragm has uniformity in pumping volume and gives a high discharge pressure (these being advantages of the plunger type reciprocating pump) and it also has resistance to leakage (which is one of the advantages of the diaphragm type reciprocating pump).

Furthermore, the above described reciprocating pump obviates a disadvantage of the plunger type reciprocating pump, namely the construction wherein the gland packing is exposed to the atomsphere. Therefore, the danger that any liquid might leak through the gland packing into the plunger drive means is obviated.

The above described reciprocating pump incorporating a plunger and a diaphragm also has the disadvantage that the volume of the small chamber formed on the plunger side between the diaphragm and an insidewall of the pump casing, changes drastically in accordance with the reciprocating motion of the plunger and the diaphragm. When the volume of the chamber is minimum, the inside pressure of the chamber will be maximum, and when the volume of the chamber is maximum, the inside pressure of the chamber will be minimum. This repeated changing of the inside pressure of the chamber causes fatigue of the diaphragm, and when the fatigue exceeds a predetermined limit, the diaphragm will burst. Also such repeated changing of the volume of air or inside pressure of the chamber wastes power for work having no connection with transporting the liquid.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a construction obviating the above disadvantage of a reciprocating pump incorporating a plunger and a diaphragm.

Another object of this invention is to provide, in a reciprocating pump incorporating a plunger and a diaphragm, a safety valve to allow liquid to escape from the cylinder chamber to a liquid inlet, when the inside pressure of the cylinder chamber exceeds a certain level.

Still another object of this invention is to provide, in a reciprocating pump incorporating a plunger and a diaphragm, a small chamber between the crosshead of the pump and an adjacent diaphragm for supplying lubricating oil to the means for driving the plunger of the pump.

To achieve these objects, the reciprocating pump according to the present invention comprises:

a pump casing including a partition defining on one side thereof a cylinder chamber having an inlet port with an inlet valve and an outlet port with an outlet valve, and on the other side thereof a second chamber;

a plunger slidably supported in said casing;

a drive means mounted in said second chamber for driving said plunger in reciprocation;

a crosshead fixed to said plunger, and constituting a part of said plunger drive means;

a diaphragm including a central portion secured between said plunger and said crosshead, and with a peripheral portion secured to said casing, said diaphragm defining a closed space with said partition; and

a hollow elastic damping body disposed in said closed space between said diaphragm and said partition, said hollow elastic body extending through said casing and having an inner space which communicates with the ambient atmosphere.

Furthermore, said plunger can have a valve chamber with a check valve therein, said check valve being opened to communicate with said cylinder chamber and said valve chamber only when the pressure inside said cylinder chamber increases to a limit value, said valve chamber being in constant communication with the inlet port.

The crosshead can be formed as a piston-like body which is reciprocatably slidable in said pump casing and the crosshead can have at least two passages communicating between said second chamber and a further chamber formed between said crosshead and said diaphragm. Each of said at least two passages has a check valve, and at least one of said check valves allows liquid to flow in one direction while at least one other allows liquid to flow only in the reverse direction.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects will be better understood from the accompanying drawing and associated description illustrating one embodiment of the present invention in detail, in which:

The sole FIGURE is a sectional view of an embodiment of the reciprocating pump according to the present invention.

DETAILED DESCRIPTION As shown in the drawing, the pump of the invention comprises a pump casing A including a cylinder chamber A, and a second chamber A for accommodating a plunger driving means, the chambers being divided by a partition A. A hollow annular plunger 1 is slidably supported within cylinder chamber A in closely fitted relation. The center portion of a diaphragm 2 is fixed to the base end of the plunger 1, and the peripheral portion of the diaphragm is secured in the outer shell of the pump casing A. In the embodiment shown in the drawing, a second diaphragm 3 is provided. The second diaphragm 3 has the same construction as the first diaphragm 2 and is fixed on a short stem 4 connected to the plunger 1. The diaphragm 3 is secured in the outer shell of the pump casing A. It is preferred that the diaphragm 3 be parallel to the diaphragm 2. One end of a crosshead 5 is connected to the short stem 4, and the other end of the crosshead 5 is pivotally connected to a slide bar 6 through a pin 7. The slide bar 6 is pivotably connected at its base end to a crank 9 which is eccentrically fixed on a crank-shaft 8, one end of which extends outside the chamber A The cylinder chamber A of the pump casing A has an inlet port H with an inlet check valve and an outlet port 13 with an outlet check valve 12. Additionally, a passage 14 extends between a location near the partition A in the cylinder chamber A, and a location upstream of the inlet check valve 10 of the inlet port 11. A safety check valve 15 is provided at the end of the plunger 1, and a passage 16 in plunger 1 serves for connecting the safety check valve 15 and the passage 14. The safety check valve 15 is spring-biassed and usually shut, but it opens when the pressure inside of the cylinder chamber A, increases to an unusually high value. Numerals l7 and 18 designate gland packings for preventing leakage of transported liquid, and numeral 19 is a lantern ring. A gland packing 20 is urged against the surface of the gland packing 18 on the side opposed to the lantern ring 19. The pressure of packing 20 on packing 18 can be adjusted by tightening or loosening an adjustment screw 21. The gland packing 20 has a ring-shaped portion 20a at one end abutting against the gland packing l8, and a disc portion 20b at the other end for receiving the pressure transmitted by the adjustment screw 21. The ring-shaped portion 200 and the disc portion 20b are connected integrally by means of a plurality of flexible legs 200.

The crosshead 5 is provided with lubricating oil passages 22 and 23 with check valves 24 and 25 respectively. The oil passes through the check valves 24 and 25 in opposite directions.

In a closed space 26 formed between the diaphragm 2 and the partition A, a hollow elastic body T is mounted for damping purposes, this being one of the most important elements of the present invention. A part of the hollow elastic body T passes through and extends out of the pump casing A, and the inside space of the hollow elastic body T communicates with the atmosphere. The portion of the hollow elastic body T in casing A is sealed by any suitable sealing means such as O-ring 27, and the space 26 is thereby sealed from the ambient atmosphere. Additionally, a space 28 is formed between the diaphragm 3 and the crosshead 5 and this space can be operated as a pump chamber of a diaphragm pump for circulating lubricating oil L. One of the diaphragms 2 and 3 can be omitted, but considering durability and safety the use of two diaphragms is prevered.

The operation of the reciprocating pump according to the present invention is as follows:

When a rotational drive motion is applied to the crank-shaft 8, the rotational motion is translated into a reciprocating motion and transmitted to the crosshead 5 and the plunger 1 connected thereto with a stroke equal to twice the eccentric radius S of the crank 9. In the drawing, during the rearward (leftward) movement of the plunger 1, the inside pressure of the cylinder chamber A. decreases, the inlet check valve 10 opens and the outlet check valve 12 closes. Accordingly, liquid in the inlet port 11 flows past the check valve 10 into the cylinder chamber A and when the plunger 1 reaches the left end position, there is sucked up in the cylinder chamber A the volume of liquid corresponding to the stroke of the plunger 1. During the forward (rightward) movement of the plunger 1, since the inside pressure of the cylinder chamber A increases, the inlet check valve 10 closes and the outlet check valve 12 opens. Accordingly, the liquid sucked into the cylinder chamber A is discharged from this chamber in an amount equal to the product of the sectional area of the plunger 1 and the stroke thereof. When the above operation is repeated, a constant volume of the liquid is transported for each stroke of the plunger 1. Leakage of the fluid from the cylinder chamber A in the direction of the chamber A is prevented by the gland packings l7 and 18, but such leakage can occur after long usage. However, since any liquid which has passed through the gland packing l8 flows through the lantern ring 19 and passage 14 and returns to the inlet port 11, it never leaks out from the pump. Furthermore, if any liquid should pass through the gland packing 17 and leaks into the closed space 26, the diaphragm 2 prevents any leakage of the liquid into the chamber A Since the volume of the closed space 26 changes periodically by the reciprocating movement of the plunger l and diaphragm 2, the inside pressure of the closed space 26 also varies in accordance with the change in volume of the space. Since varying the inside pressure of the closed space 26 applies repeated stress to the diaphragm 2, it may happen that the diaphragm may burst with fatigue after being in use a long term, and the liquid flows in the direction of the chamber A If some small holes communicating with the atmosphere are provided in the wall of the space 26, such fear can be eliminated, but in such case any liquid passing the gland packing 17 may leak outside of the pump casing, while dust may enter the chamber. Therefore, the provision of holes in the wall of the space 26 is not desirable.

in the present invention, the hollow elastic damping body T (which is of ring-shape or other shape) and communicates with the atmosphere is mounted in the closed space 26 and when the inside pressure of the closed space 26 increases, the value of the hollow elastic body T decreases in accordance with the increased inside pressure of the space 26, and the air occupying the inside of the hollow elastic body T is exhausted into the atmosphere. When the volume of the closed space 26 increases in accordance with the leftward movement of the plunger 1 and the diaphragm 2, and therefore the inside pressure of the closed space 26 decreases, the volume of the hollow elastic body T increases by means of the air sucked into the body. Hence, by the provision of the hollow elastic body T in the closed space 26, the magnitude of the change in volume and pressure of the interior space 26 is greatly reduced, and therefore, the durability of the diaphragm 2 is greatly increased. Since the portion of the hollow elastic body T extending in the casing wall is sealed by the O-ring 27, there is no fear that any liquid which has passed through the gland packing will leak outside to the pump casing.

The operation of the safety valve 15 in the plunger 1 will now be explained.

First, the'case without the safety valve 15 will be considered. If the liquid flow stops suddenly as the result of an accident downstream of the outlet port 13, after starting rightward movement of the plunger 1, the outlet check valve 12 may not open. In such case, the inside pressure of the cylinder chamber A will increase abnormally, and the plunger driving means will be subjected to an over-load which may cause some type of damage such as overheating of the motor coils. However, in the present invention, since the safety valve 15 is provided in the plunger 1, when the inside pressure of the cylinder chamber A, exceeds an allowable limit, the safety valve opens and the liquid in the cylinder chamber A, returns to the inlet port 11 through the passage 16 in the plunger 1, the lantern ring 19 and the passage 14, and therefore any type of damage can be prevented. it is to be noted that lantern ring 19 provides for constant communication between passages 14 and 16.

By the provision of both the crosshead 5 formed as the piston-like body reciprocatably slidable in said pump casing, and the provision of at least two passages 22 and 23 with check valves 24, 25 respectively in the crosshead, the space 28 can be used as a diaphragm pump for circulating the lubricating oil in the plunger driving means A In the described construction, one of the diaphragms 2 and 3 can be omitted, but considering the possibility of damage to a single diaphragm, the use of two diaphragms, is preferred. Moreover, when two diaphragms are used, if one of the two diaphragms is damaged, the function of the pump is not affected.

What is claimed is:

l. A reciprocating pump comprising:

a pump casing including a partition defining on one side thereof a cylinder chamber having an inlet port with an inlet valve and an outlet port with an outlet valve, and on the other side thereof a second chamber; plunger slidably supported in said casing;

a drive means mounted in said second chamber for driving said plunger in reciprocation;

a crosshead fixed to said plunger, and constituting a part of said plunger driving means;

a diaphragm including a central portion secured between said plunger and said crosshead, and with a peripheral portion secured to said casing, said diaphragm defining a closed space with said partition; and

a hollow elastic damping body disposed in said closed space between said diaphragm and said partition, said hollow elastic body extending through said casing and having an inner space which communicates with the ambient atmosphere.

2. A reciprocating pump according to claim 1, wherein said crosshead comprises a piston-like body reciprocatably slidable in said pump casing.

3. A reciprocating pump according to claim 1, wherein said diaphragm defines a second space with said crosshead, said crosshead having at least two passages for connecting the second space with said second chamber, a check valve for each of said at least two passages, at least one of said check valves allowing liquid to flow only from said second space to said second chamber and at least one other check valve allowing liquid to flow in reverse direction from said second chamber to said second space.

4. A reciprocating pump according to claim 1, comprising sealing means between said elastic damping body and said casing.

5. A reciprocating pump according to claim 1, comprising a second diaphragm between the first diaphragm and said cross-head, the two diaphragms being parallel to one another.

6. A reciprocating pump according to claim 1, wherein said hollow elastic body is tubular.

7. A reciprocating pump according to claim 1, wherein said plunger has a valve chamber therein communicating with said inlet port through a fluid passage, said valve chamber including a check valve which is normally closed, but which is opened and thereby causes said cylinder chamber to communicate with said inlet port through said valve chamber and fluid passage when the pressure inside said cylinder chamber increases to a predetermined excessive value.

8. A reciprocating pump according to claim 7, wherein the fluid passages from the valve chamber to the inlet port opens into the latter downstream of the valve in the inlet port.

9. A reciprocating pump according to claim 8, wherein said fluid passage includes a passageway provided in said plunger leading to the valve chamber.

10. A reciprocating pump according to claim 9, wherein said fluid passage includes a passageway extending externally of the casing and connected to the first said passageway and to said inlet port. 

1. A reciprocating pump comprising: a pump casing including a partition defining on one side thereof a cylinder chamber having an inlet port with an inlet valve and an outlet port with an outlet valve, and on the other side thereof a second chamber; a plunger slidably supported in said casing; a drive means mounted in said second chamber for driving said plunger in reciprocation; a crosshead fixed to said plunger, and constituting a part of said plunger driving means; a diaphragm including a central portion secured between said plunger and said crosshead, and with a peripheral porTion secured to said casing, said diaphragm defining a closed space with said partition; and a hollow elastic damping body disposed in said closed space between said diaphragm and said partition, said hollow elastic body extending through said casing and having an inner space which communicates with the ambient atmosphere.
 2. A reciprocating pump according to claim 1, wherein said crosshead comprises a piston-like body reciprocatably slidable in said pump casing.
 3. A reciprocating pump according to claim 1, wherein said diaphragm defines a second space with said crosshead, said crosshead having at least two passages for connecting the second space with said second chamber, a check valve for each of said at least two passages, at least one of said check valves allowing liquid to flow only from said second space to said second chamber and at least one other check valve allowing liquid to flow in reverse direction from said second chamber to said second space.
 4. A reciprocating pump according to claim 1, comprising sealing means between said elastic damping body and said casing.
 5. A reciprocating pump according to claim 1, comprising a second diaphragm between the first diaphragm and said cross-head, the two diaphragms being parallel to one another.
 6. A reciprocating pump according to claim 1, wherein said hollow elastic body is tubular.
 7. A reciprocating pump according to claim 1, wherein said plunger has a valve chamber therein communicating with said inlet port through a fluid passage, said valve chamber including a check valve which is normally closed, but which is opened and thereby causes said cylinder chamber to communicate with said inlet port through said valve chamber and fluid passage when the pressure inside said cylinder chamber increases to a predetermined excessive value.
 8. A reciprocating pump according to claim 7, wherein the fluid passages from the valve chamber to the inlet port opens into the latter downstream of the valve in the inlet port.
 9. A reciprocating pump according to claim 8, wherein said fluid passage includes a passageway provided in said plunger leading to the valve chamber.
 10. A reciprocating pump according to claim 9, wherein said fluid passage includes a passageway extending externally of the casing and connected to the first said passageway and to said inlet port. 